Halbach-array radial stabilizer for a passive magnetic bearing

• US 10,447,110 B2
• Filed: 06/01/2016
• Issued: 10/15/2019
• Est. Priority Date: 06/01/2016
• Status: Active Grant

• Current Assignee: Lawrence Livermore National Security LLC (Government of the United States of America)
• Original Assignee: Lawrence Livermore National Security LLC (Government of the United States of America)
• Inventors: Post, Richard F
• Primary Examiner(s): Truong, Thomas
• Application Number:
  US15/170,864
• Publication Number:
  US 20170353078A1
• Time in Patent Office: 1,231 Days
• Field of Search: 310 905
• CPC Class Codes: F16C 32/041 with permanent magnets on one part attracting the other part
• CPC Class Codes: F16C 32/0436 with a conductor on one part movable with respect to a magnetic field, e.g. a body of copper on one part and a permanent magnet on the other part
• CPC Class Codes: H02K 11/26 Devices for sensing voltage, or actuated thereby, e.g. overvoltage protection devices
• CPC Class Codes: H02K 7/09 with magnetic bearings

Abstract

A radial stabilizer is provided for stabilizing levitation passive bearing elements against lateral displacements. The stabilizer provides a means to introduce anisotropy in the radial stiffness of the stabilizer. The presence of anisotropic stiffness has a strongly stabilizing effect on whirl-type rotor-dynamic instabilities. The stabilizer design also provides a means for continuously monitoring the state of health of the rotor by signaling the onset of changes of balance that would be expected to precede any major failure.

Claims

1. An apparatus, comprising:

a cylinder having an outer wall characterized as having four quadrants and further having a central longitudinal axis;

a separate winding located on each quadrant, wherein each winding comprises a positive output, wherein the positive output of the windings located on geometrically opposite quadrants are connected together;

a rotor comprising an inner wall configured to rotate around said cylinder;

a Halbach array attached to the inner wall of said rotor and configured to concentrate its magnetic field near the inner surface of the array;

a first inductor coil connected between the positive output of a first set of windings located on geometrically opposite quadrants; and

a second inductor coil connected between the positive output of a second set of windings located on geometrically opposite quadrants, wherein an inductance of said first inductor coil is different from that of said second inductor coil.

2. The apparatus of claim 1, wherein when the rotor is rotating and a center of rotation of said rotor coincides with said central longitudinal axis, induced voltages between the connected windings approaches zero, and wherein when the rotor is rotating and a center of rotation of said rotor does not coincides with said central longitudinal axis, induced voltage between the connected windings increases exponentially with displacement of said center of rotation from said central longitudinal axis.

3. The apparatus of claim 1, wherein when the rotor is rotating and a center of rotation of said rotor coincides with said central longitudinal axis, induced voltages between the connected windings approaches zero, and wherein when the rotor is rotating and a center of rotation of said rotor does not coincides with said central longitudinal axis, induced voltage between the connected windings increases exponentially with displacement of said center of rotation from said central longitudinal axis.

4. The apparatus of claim 1, wherein each said separate winding comprises zig-zag pattern.

5. The apparatus of claim 4, wherein zig-zag pattern comprises a square wave pattern or a rectangular wave pattern.

6. The apparatus of claim 5, wherein a spacing between each leg of said pattern is congruent with a half-wavelength of said Halbach array.

7. An apparatus, comprising:

a cylinder having an outer wall and a central longitudinal axis, wherein said outer wall can be characterized as having four quadrants that altogether span the circumference of said outer wall such that a first quadrant is adjacent to a second quadrant which is adjacent to a third quadrant which is adjacent to a fourth quadrant which is adjacent to said first quadrant, wherein said first quadrant is on the opposite side of said axis from said third quadrant and wherein said second quadrant is on the opposite side of said axis from said fourth quadrant;

a first winding located on said first quadrant and not on the other quadrants, said first winding having a first negative lead and a first positive lead, wherein said first negative lead is grounded;

a second winding located on said second quadrant and not on the other quadrants, said second winding having a second negative lead and a second positive lead, wherein said second negative lead is grounded;

a third winding located on said third quadrant and not on the other quadrants, said third winding having a third negative lead and a third positive lead, wherein said third negative lead is grounded, wherein said first positive lead and said third positive lead are connected together;

a fourth winding located on said fourth quadrant and not on the other quadrants, said fourth winding having a fourth negative lead and a fourth positive lead, wherein said fourth negative lead is grounded, wherein said second positive lead and said fourth positive lead are connected together;

a rotor having an inner wall, wherein said rotor is configured to rotate around said cylinder;

a Halbach array attached to the inner wall of said rotor and configured to concentrate its magnetic field near the inner surface of the array

a first inductor coil having a first inductor lead and a second inductor lead; and

a second inductor coil having a third inductor lead and a fourth inductor lead, wherein said first positive lead is connected to said first inductor lead, wherein said second inductor lead is connected to said third positive lead, wherein said second positive lead is connected to said third inductor lead and wherein said fourth inductor lead is connected to said fourth positive lead, wherein an inductance of said first inductor coil is different from that of said second inductor coil.

8. The apparatus of claim 7, wherein said Halbach array is configured to concentrate its magnetic field near the inner surface of the array such that said magnetic field can interact with said first winding, said second winding, said third winding and said fourth winding, wherein when the rotor is rotating and the center of rotation of said rotor coincides with said central longitudinal axis, (i) the induced voltage between said first positive lead and said third positive lead approaches zero and (ii) the induced voltage between said second positive lead and said fourth positive lead approaches zero, and wherein when the rotor is rotating and the center of rotation of said rotor does not coincides with said central longitudinal axis, (i) the induced voltage between said first positive lead and said third positive lead increases exponentially with displacement of said center of rotation from said central longitudinal axis and (ii) the induced voltage between said second positive lead and said fourth positive lead increases exponentially with displacement of said center of rotation from said central longitudinal axis.

9. The apparatus of claim 7, wherein each of said first winding, said second winding, said third winding and said fourth winding comprises zig-zag pattern.

10. The apparatus of claim 9, wherein zig-zag pattern comprises a square wave pattern or a rectangular wave pattern.

11. The apparatus of claim 10, wherein a spacing between each leg is congruent with a half-wavelength of said Halbach array.

12. The apparatus of claim 7, wherein said first positive lead is adjacent to said second negative lead, wherein said second positive lead is adjacent to said third negative lead, wherein said third positive lead is adjacent to said fourth negative lead, wherein said fourth positive lead is adjacent to said first negative lead.